Telescoping crane boom

ABSTRACT

Means and method for extending a telescopic crane boom section of a mobile crane that does not have its own extending cylinder are disclosed. The crane boom comprises four tubular telescopic sections, namely, a first fly section, second and third sections, and a fourth base section. First and second linearly extendable hydraulic rams are located within the boom. The first ram is connected between the base section and the third section to effect movement of the latter. The second ram is connected between the third and second sections to effect movement of the latter. For road transport conditions, the fly section is detachably connected to the second section. To set up the crane for operation, the first ram is used to partially extend the three movable sections. Then the second ram is used to further extend the first two sections. The first ram is then temporarily attached to the fly section and the fly section is disconnected from the second section. The second ram is then used to retract the second section, the fly section is then connected to the second section in fully extended position, and the first ram is then disconnected from the fly section. Both rams are now in readiness to independently operate the second and third sections, with the fly section fully extended on the second section.

United States Paten 1191 Johnston 1451 Mar. 5, 1974 1 TELESCOPING CRANE BOOM [75] lnventor: Roger L. Johnston, Marion, Iowa [73] Assignee: Harnischfeger Corporation,

Milwaukee, Wis.

22 Filed: May 18,1972

[21] Appl. No.: 254,665

52 us. c1. 212/55 Primary ExamirierEvon C. Blunk Assistant ExaminerDouglas D. Watts Attorney, Agent, or Firm-James E. Nilles [57 ABSTRACT Means and method for extending a telescopic crane boom section of a mobile crane that does not have its own extending cylinder are disclosed. The crane boom comprises four tubular telescopic sections, namely, a first fly section, second and third sections, and a fourth base section. First and second linearly extendable hydraulic rams are located within the boom. The first ram is connected between the base section and the third section to effect movement of the latter. The second ram is connected between the third and second sections to effect movement of the latter. For road transport conditions, the fly section is detachably connected to the second section. To set up the crane for operation, the first ram is used to partially extend the three movable sections. Then the second ram is used to further extend the first two sections. The first ram is then temporarily attached to the fly section and the fly section is disconnected from the second sec 5 Claims, 15 Drawing Figures PATENTEDMR 51914 3.795.321

SHEET E OF 5 FIG. 1A

PATENTED MAR 5 I974 SKUBUFS mTO PATENTEBHAR 51974 SHEET W 0F 5 PATENTED 51974 SHEU 0F 5 TELESCOPING CRANE BOOM BACKGROUND OF THE INVENTION 1. Field of Use This invention relates generally to multi-section hydraulically operated telescopic booms such as used on mobile cranes or the like. In particular, it relates to means and method for extending and retracting the outermost fly section of the crane which does not have its own hydraulic operating cylinder or ram.

2. Description of the Prior Art Various types of multi-section hydraulically operated telescopic crane booms are known and in use. Such booms need to be extended to great lengths and be able to handle very heavy loads but alsomust be relatively light and compact to facilitate their mobility. Accordingly, it is customary to design such cranes so that, in operation, the fly section is permanently extended and, for weight and economy, to rely on means other than a separate hydraulic ram to extend and retract the fly section. U. S. Pat. No. 3,368,696 issued Feb. 13, 1968 to R. L. Johnston et al. for Telescopic Crane Booms discloses a crane boom of the general type under consideration. With crane booms of this type it is desirable to provide a means and method which facilitate extension of the fly section in the simplest and most rapid manner.

SUMMARY OF THE PRESENT INVENTION The means and method for extending and retracting the fly section ofa telescopic boom in accordance with the invention contemplate a crane boom having four tubular telescopic sections, namely, a first or fly section telescopic within a second section which, in turn, is telescopic within a third section which, in turn, is telescopic within a fourth or base section. The base section is adapted to be mounted for vertically pivotable movement on a horizontally rotatable crane upper mounted, for example, on a mobile crane unit.

First and second linearly extendable and. retractable power means, such as hydraulic cylinder or rams, are located within the fly section when the boom is telescoped. Each ram comprises a stationary portion and a movable portion. The stationary portion of the first ram is connected to the inner end of the base section and the inner end of the movable portion of the first ram is connected to the inner end of the third section. The outer end of the movable portion of the first ram is releasably connectible to the inner end of the fly section. The stationary portion of the second ram is connected to the inner end of the third section and the inner end of the movable portion of the second ram is connected to the inner end of the second section.

The first, second and third boom sections are provided with pin holes and access holes, as hereinafter explained, which accommodate removable pin means which permit selective connection of the boom sections and the outer end of the movable portion of the first ram.

In transport position, all boom sections are telescopcd, the outer ends of the first and second sections are connected by first pin means, and the outer end of the movable portion of the first ram is unconnected. To set up the boom for operation, the first ram is operated to partially extend the first, second and third sections from the base section and to expose a clearance or access hole in the third section. Then, the second ram is operated to extend the first and second sections out of the third section until a clearance hole in the second section and a pin hole in the first section are aligned with the clearance hole in the third section and with a pin hole in the outer end of the movable portion of the first ram. A second pin means is then employed through the clearance hole to secure the inner end of the fly section to the outer end of the movable portion of the first ram. The first pin means are removed to disconnect the first and second sections. The second ram is operated to retract the second section so that the inner end of the first section can be secured through the clearance holes by third pin means to the outer end of the second section. The second pin means are then removed to disconnect the movable portion of the first rarn from the first section. The first or fly section is now secured by the third pin means to the second section in fully extended position and the second and third sections can be operated at will by the second and first rams, respectively. To return the boom to transport position, a procedure opposite to that described is employed.

DRAWINGS FIG. 1A is a perspective view of a mobile crane employing a crane boom in accordance with the invention;

FIG. 1 is a side elevational'view of a crane boom in accordance with the invention showing it in horizontal position and with the first three sections partially extended from the base section to expose a clearance hole in the third section;

FIG. 2 is a cross-sectional view of the boom in the position shown in FIG. 1;

FIGS. 3, 4, 5 and 6 are cross-sectional views of the boom taken on the lines 33, 4-4, 5-5 and 66 of FIG. 2;

FIG. 7 is a side elevational view of the boom showing the first and second sections extended from the third section;

FIG. 8 is a cross-sectional view of the boom in the position shown in FIG. 7;

FIG. 9 is a cross-sectional view of the boom taken on line 99 of FIG. 8;

FIG. 10 is a side elevational view of the boom showing the first section extended and the second section retracted into the third section;

FIG. 11 is a cross-sectional view of the boom in the position shown in FIG. 10;

FIG. 12 is a cross-sectional view of the boom taken on line I2-l2 of FIG. 11',

FIG. 13 is a side elevational view of the boom showing all sections extended; and

FIG. 14 is a cross-sectional view of the boom in the position shown in FIG. 13.

DESCRIPTION OF A PREFERRED EMBODIMENT Construction Referring to FIGS. 1A and l of the drawings, there is shown a telescoping crane boom in accordance with the invention and disposed in horizontal position. The boom comprises a tubular first or fly section I, a tubular second section 2 in which first section 1 telescopes, a tubular third section 3 in which second section 2 telescopes, and a tubular fourth or base section 4 in which third section 3 telescopes. Fly section 1 is provided at its outer end with a head 20 on which, for example, a pulley or other working device can be mounted. Base section 4 is provided at its inner end with a mounting bracket 22 by means of which it can be secured for vertical pivotal movement to a horizontally rotatable portion 24 of a mobile crane 26.

As FIG. 2 shows, first and second linearly extendable power means, in the form of hydraulic cylinders or rams 6 and 5, are located within fly section 1. As FIGS. 2 and 3 show, first ram 6 comprises a movable portion 6B which has its inner end connected by a pin D to the inner end of third section 3. As FIGS. 2 and 5 show, the movable portion 68 of first ram 6 has a pin hole 8 at its outer end.

As FIG. 2 shows, second ram 5 comprises a stationary portion 5A which is connected by a pin C to the inner end of third section 3. Second ram 5 also com prises a movable portion 5B which has its inner end connected by a pin B to the inner end of second section 2.

The rams 5 and 6 are understood to be operable to extended and retracted positions by conventional hydraulic control means.

Each boom section is hollow and of rectangular cross sectional configuration.

As FIG. 14 shows, fly section 1 is provided with a pair of pinning holes 7 near its outer end; with a pair of pinning holes 10 near its inner end; and with a pair of pinning holes 9 intermediate pinning holes 7 and 10.

As FIGS. 13 and 14 show, second section 2 is provided with a pair of pinning holes 15 near its outer end and with pairs of access or clearance holes 12 and 13; the access holes 12 being nearer the inner end of the second section 2.

As FIG. 13 shows, a third section 3 is provided with a pair of access or clearance holes 11 near its outer end which are always in registry with pinning hole 8 in first ram 6.

The pinning holes and access holes hereinbefore described are adapted to receive manually insertable and removable pin means hereinafter identified. Since the boom sections have access holes and pinning holes on opposite sides, the pin means can be inserted from eithcr side.

. Third section 3 is movable out of fourth section 4 to a position wherein its access holes 11 are visible and accessible. Furthermore, when sections 1 and 2 are aligned so that the pin holes 7 in the former are in registry with the pin holes 15 in the latter, the pin holes 10 in fly section 1 are also aligned with the access holes 12 in second section 2.

Operation The method of extending and retracting the crane boom disclosed herein will now be described. Assume that all retractable boom sections are retracted and that the boom is in horizontal position. Also assume, as FIG. 6 shows, that a first pin 16 is inserted in the pinning holes 7 in fly section 1 and the pinning holes 15 in the second section 2 to secure sections 1 and 2 together. The method to extend fly section 1 (which does not have its own extending ram) to place the boom in readiness for operation is as follows. In the following description, for convenience, only one pinning hole and one access hole of each pair will be referred to.

Using ram 6, extend the first, second and third boom sections 1, 2, and 3, respectively, out of fourth section 4 until clearance hole 11 in third section 3 is visible, and accessible as shown in FIGS. 1, 2 and 5.

Using ram 5, extend the first and second boom sections 1 and 2 out of third section 3 until the clearance hole 12 in second section 2 and pinning hole 10 in fly section 1 are aligned with pinning hole 8 on ram 6 and with clearance hole 11 on third section 3. Insert a second pin 17 through the clearance holes 11 and 12 into pinning hole 10 in fly section 1 and pinning hole 8 on ram 6, thus connecting ram 6 to fly section 1, as shown in FIGS. 7, 8 and 9.

Now remove first pin 16 from holes 7 and 15 thereby eliminating the connection between first and second sections 1 and 2, respectively.

Using ram 5, retract second section 2 until the pinning hole 15 in second section 2 (that was previously aligned with pinning hole 7 in first section 1) aligns with pinning hole 9 in first section 1. Insert a third pin 18 into pinning hole 9 in section 1 and pinning hole 15 in section 2, thus connecting first and second sections 1 and 2, respectively, with fly section 1 in fully extended position, as shown in FIGS. 10, 11 and 12.

Now remove the second pin 17 from hole 8 on ram 6 and hole 10 on fly section 1 through clearance hole 13 in second section 2 and clearance hole 11 in third section 3, eliminating the connection between ram 6 and fly section 1.

Fly section 1 is now fixed in its extended position and second and third sections 2 and 3, respectively, which have their own powering rams 5 and 6, respectively, can be fully extended (as shown in FIGS. 13 and 14) or telescoped at will (with fly section always fully extended.

Now assume that the boom is in the condition aforedescribed and that it is described to place it in readiness for road transport. To do so, the following procedural steps are followed.

Using first ram 6, place third section 3 so that access hole 11 is visible and accessible beyond the outer end of fourth section 4. Using second ram 5, operate second section 2 to align access hole 13 therein with access hole 11 in third section 3. Insert second pin means 17 through the access holes 11 and 13 into the pin hole 10 on fly section 1 and the pin holes 8 on ram 6 to secure section 1 and ram 6 together. Remove third pin means 18 from the pin hole 9 on fly section 1 and the pin hole 15 on section 2. Using second ram 5, extend second section 2 until pinning hole 15 in second section 2 (that was previously aligned with pinning hole 9 in first section 1) aligns with pinning hole 7 in first section 1, and access hole 12 in second section 2 is in registry with access hole 11 in third section 3. Insert first pin means 16 into pinning hole 15 in second section 2 and pinning hole 7 in first section 1, to secure the first and second sections 1 and 2 with the former telescoped within the latter. Remove second pin means 17 to disconnect fly section 1 and ram 6. Using second ram 5, retract second section 2 into third section 3. Using first ram 6, completely retract section 3 into fourth section 4 and the boom is ready for transport.

I claim:

I. In a telescopic boom having a fly section, a second section, a third section and a base section,

said third section being provided with at least one access hole therein, said second section being provided with a pinning hole near its outer end and with two spaced apart access holes, and said fly section being provided with pinning holes, one near each end and with another pinning hole intermediate thereof,

a first extendable and retractable hydraulic actuator comprising two relatively movable portions, one portion being connected to the inner end of said base section and the other portion being connected to the inner end of said third section,

a second extendable and retractable hydraulic actuator comprising two relatively movable portions, one portion being connected to the inner end of said third section and the other portion connected to the inner end of said second section,

first means for releasably connecting said fly section and said second section with the former retracted within the latter,

second means for releasably connecting said other portion of said first actuator to the inner end of said fly section,

and third means for releasably connecting said fly section and said second section to each other with the former extended from the latter, said first, second and third means comprising removable pin means.

2. A boom according to claim 1 wherein the outer end of said first actuator is provided with a pinning hole and wherein, when the access hole in said third section is aligned with the access hole nearer the inner end of said second section when the pinning holes near the outer ends of the fly section and the second section are aligned, the pinning hole near the inner end of said fly section is aligned with said pinning hole in said first actuator and is accessible through the access hole in said third section and the access hole nearer the inner end of said second section.

3. A boom according to claim 2 wherein, when the pinning hole near the outer end of the second section is aligned with the intermediatepinning hole of said fly section, the primary hole near the inner end of said fly section is accessible through the access hole in said third section and through the access hole in the second section which is nearer the outer end of the second section.

4. In a telescopic boom having a fly section, a second section, a third section and a base section, said third section being provided with at least one access hole therein, said second section being provided with a pinning hole near its outer end and with two spaced apart access holes, and said fly section being provided with pinning holes, one near each end and with another pinning hole intermediate thereof,

a first extendable and retractable hydraulic actuator connected between the inner end of said base section and the inner end of said third section, said first actuator being provided with a pinning hole,

a second extendable and retractable hydraulic actuator connected between the inner end of said third section and the inner end of said second section,

first means comprising removable pin means for releasably connecting said fly section and said second section with the former retracted within the latter,

second means comprising removable pin means for releasably connecting said first actuator to the inner end of said fly section,

and third means comprising removable pin means for releasably connecting said fly section and said second section with the former extended from the latter, and wherein when the access hole in said third section is aligned with the access hole nearer the inner end of said second section when the pinning holes near the outer ends of the fly section and the second section are aligned, the pinning hole near the inner end of said fly section is aligned with said pinning hole in said first actuator and is accessible through the access hole in said third section and the access hole nearer the inner end of said second section.

5. A boom according to claim 4, wherein, when the pinning hole near the outer end of the second section is aligned with the intermediate pinning hole of said fly section, the primary hole near the inner end of said fly section is accessible through the access hole in said third section and through the access hole in the second section which is nearer the outer end ofthe second section. 

1. In a telescopic boom having a fly section, a second section, a third section and a base section, said third section being provided with at least one access hole therein, said second section being provided with a pinning hole near its outer end and with two spaced apart access holes, and said fly section being provided with pinning holes, one near each end and with another pinning hole intermediate thereof, a first extendable and retractable hydraulic actuator comprising two relatively movable portions, one portion being connected to the inner end of said base section and the other portion being connected to the inner end of said third section, a second extendable and retractable hydraulic actuator comprising two relatively movable portions, one portion being connected to the inner end of said third section and the other portion connected to the inner end of said second section, first means for releasably connecting said fly section and said second section with the former retracted within the latter, second means for releasably connecting said other portion of said first actuator to the inner end of said fly section, and third means for releasably connecting said fly section and said second section to each other with the former extended from the latter, said first, second and third means comprising removable pin means.
 2. A boom according to claim 1 wherein the outer end of said first actuator is provided with a pinning hole and wherein, when the access hole in said third section is aligned with the access hole nearer the inner end of said second section when the pinning holes near the outer ends of the fly section and the second section are aligned, the pinning hole near the inner end of said fly section is aligned with said pinning hole in said first actuator and is accessible through the access hole in said third section and the access hole nearer the inner end of said second section.
 3. A boom according to claim 2 wherein, when the pinning hole near the outer end of the second section is aligned with the intermediate pinning hole of said fly section, the primary hole near the inner end of said fly section is accessible through the access hole in said third section and through the access hole in the second section which is nearer the outer end of the second section.
 4. In a telescopic boom having a fly section, a second section, a third section and a base section, said third section being provided with at least one access hole therein, said second section being provided with a pinning hole near its outer end and with two spaced apart access holes, and said fly section being provided with pinning holes, one near each end and with another pinning hole intermediate thereof, a first extendable and retractable hydraulic actuator connected between the inner end of said base section and the inner end of said third section, said first actuator being provided with a pinning hole, a second extendable and retractable hydraulic actuator connected between the inner end of said third section and the inner end of said second section, first means comprising removable pin means for releasably connecting said fly section and said second section with the former retracted within the latter, second means comprising removable pin means for releasably connecting said first actuator to the inner end of said fly section, and third means comprising removable pin means for releasably connecting said fly section and said second section with the former extended from the latter, and wherein when the access hole in said third section is aligned with the access hole nearer the inner end of said second section when the pinning holes near the outer ends of the fly section and the second section are aligned, the pinning hole near the inner end of said fly section is aligned with said pinning hole in said first actuator and is accessible through the access hole in said third section and the access hole nearer the inner end of said second section.
 5. A boom according to claim 4, wherein, when the pinning hole near the outer end of the second section is aligned with the intermediate pinning hole of said fly section, the primary hole near the inner end of said fly section is accessible through the access hole in said third section and through the access hole in the second section which is nearer the outer end of the second section. 